Photochemistry of radical ions with irradiation of electron and laser pulses

电子和激光脉冲照射下自由基离子的光化学

• 批准号: 07455341
• 负责人: MAJIMA Tetsuro
• 金额: $ 5.06万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07455341/
• 关键词: Radiation chemistry; Photochemistry; Radical ions

Photophysical and chemical properties of radical ions of aromatic compounds in the excited states have been clarified by a pulse radiolysis-laser flash photolysis combined method. The lifetimes of radical cations and anions of cis- and trans-stibene (c-St and t-St) and radical anions of dicyanoanthracene, phenazine, and anthraquinones in the excited states were measured for the first time and their transient phenomena such as the photoelectron ejection, c-t isomerization, and selective hole and electron transfer quenching of the radical cations and anions in the excited states, respectively, were investigated. In the deactivation of radical cations of c-St in the excited doublet state (c-St^<*+**>), the internal conversion competes with the isomerization to t-St^<*+> in a quantum yield of 0.49, whereas t-St^<*+**> is only deactivated via internal conversion. Lifetimes of t-St^<*+**> and c-St^<*+**> are estimated to be approximately 240 and 120 ps, respectively. The shorter lifetime of … More c-St^<*+**> is attributed to isomerization and conversion to another product via twisting about the central C=C double bond. St radical anions in the excited doublet state (St^<*-**>) undergo unimolecular isomerization from c-St^<*-> to t-St^<*->, photoelectron ejection, and electron transfer to biphenyl added as a quencher. From the selective electron transfer from St^<*-**> to biphenyl (Bp), the lifetimes of c-St^<*-**> and t-St^<*-**> are estimated to be approximately 1.5 and 2.5 ns, respectively. The shorter tau of c-St^<*-**> is attributed to isomerization via twisting about the central C=C double bond. The tau values of c-St^<*-**> and t-St^<*-**> are 1 order of magnitude longer than those of c-St^<*+**> and t-St^<*+**>. Lifetimes of approximately 4 ns are estimated for M^<*-**> (M=dicyanoanthracene, phenazine, and anthraquinones). The shorter lifetimes of 1.0-1.4 ns for methyl and chloro substituents on anthraquinone are explained in terms of internal conversion accelerated by rotatio of the substituents. The energy gap between the excited and ground states of M^<・-> is a singnficant factor for the rate of the internal conversion. A solvated pair of M and quencher^<・-> is suggested as an intermediate in the electron-transfer quenching of M^<*-**> by quencher such as fumaronitile. Less

用脉冲辐解-激光闪光光解联合方法研究了芳香族化合物自由基离子激发态的光物理化学性质。首次测量了顺式和反式二苯乙烯（c-St和t-St）自由基阳离子和阴离子以及二氰基蒽、吩嗪和蒽醌自由基阴离子的激发态寿命，并研究了它们的瞬态现象，如激发态的光电子发射、c-t异构化、空穴和电子转移的选择性猝灭.在激发态双峰态（c-St^<*+**>）的c-St的自由基阳离子的失活中，内转化与异构化成t-St^<*+>竞争，量子产率为0.49，而t-St^<*+**>仅通过内转化失活。t-St^<*+**>和c-St^<*+**>的寿命估计分别约为240和120 ps。寿命较短的 ...更多信息 c-St^<*+**>归因于异构化和通过围绕中心C=C双键扭转转化为另一种产物。处于激发二重态（St^*-**>）的St自由基阴离子经历从c-St^*->到t-St^*->的单分子异构化、光电子发射和电子转移到作为猝灭剂添加的联苯。从St^*-**>到联苯（Bp）的选择性电子转移，c-St^*-**>和t-St^*-**>的寿命分别估计为约1.5和2.5 ns。c-St <*-**>的较短τ归因于经由围绕中心C=C双键的扭曲的异构化。c-St^<*-**>和t-St^<*-**>的τ值比c-St^<*+**>和t-St^<*+**>的τ值长1个数量级。估计M^*（M=二氰基蒽、吩嗪和蒽醌）的寿命约为4 ns。蒽醌上的甲基和氯取代基的寿命较短（1.0- 1.4ns），这是由于取代基的旋转加速了内转换。激发态和基态之间的能隙是影响内转换速率的重要因素。M和猝灭剂的溶剂化对被认为是猝灭剂如蒙脱石对M **-**>的电子转移猝灭的中间体。少

项目成果

Tetsuro Majima: "Cis-trans isomerization and Oxidation of Radical Cations of Stilbene Derivatives" J. Org. Chem.61・22. 7793-7800 (1996)

真岛哲郎：“二苯乙烯衍生物的顺反异构化和自由基氧化”J. Org. 7793-7800 (1996)

Tetsuro Majima: "Formation of Dimer Radical Anions of Aromatic Acetylenes During Pulse Radiolysis and γ-Radiolysis" J.Phys.Chem.101. 1048-1055 (1997)

Tetsuro Majima：“脉冲辐射分解和 γ-辐射分解过程中芳香族乙炔二聚体自由基阴离子的形成”J.Phys.Chem.101 1048-1055 (1997)。

Akito Ishida: "Lifetimes and Transient Phenomena of Stilbene Radical Cations in the Second Doublet Excited State" J. Phys. Chem.99. 10808-10814 (1995)

Akito Ishida：“二苯乙烯自由基阳离子在第二双激发态的寿命和瞬态现象”J. Phys。

Tetsuro Majima, Sachiko Tojo, Akito Ishida, and Setsuo Takamuku: "Reactivities of Isomerization, Oxidation, and Dimerization of Radical Cations of Stibene Derivatives" J.Phys.Chem.100-32. 13615-13623 (1996)

Tetsuro Majima、Sachiko Tojo、Akito Ishida 和 Setsuo Takamuku：“苯乙烯衍生物自由基阳离子异构化、氧化和二聚反应的反应性”J.Phys.Chem.100-32。

Setsuo Takamuku, Tetsuro Majima, Akito Ishida, and Sachiko Tojo: "Mechanistic Aspects of Chemical Reactivities of Aromatic Radical Ions in the Ground and Excited States" Mem.Inst.Sci.Ind.Res.Osaka Univ.(in press).

Setsuo Takamuku、Tetsuro Majima、Akito Ishida 和 Sachiko Tojo：“芳香自由基离子在基态和激发态化学反应性的机理”Mem.Inst.Sci.Ind.Res.Osaka Univ.（印刷中）。